Endodontic systems and methods for preparing apical portions of root canals with a set of files having large tapers

ABSTRACT

An apical portion of a root canal is cleaned with an abrading portion of a file that has a taper that is greater than 0.20. Once the apical portion has been cleaned with an abrading portion that is greater than 0.20, such as 0.25, then an endodontic point, such as a gutta percha point can be easily received in the apical portion of the root canal to seal the apex. It is optimal to utilize a set of instruments. All of the instruments may have files with abrading portions that are greater than 0.25. However, only the larger files need have such abrading portions since they are the last to be used when cleaning the apical portion.

RELATED APPLICATIONS

[0001] This application is a continuation-in-part of U.S. patentapplication Ser. No. 09/736,729 entitled Endodontic Sealing Compositionsand Methods for Using Such Compositions which was filed on Dec. 14,2000. This application is also a continuation-in-part of U.S. patentapplication Ser. No. 09/753,981 entitled Endodontic System and Methodsfor the Anatomical, Sectional and Progressive Corono-Apical Preparationof Root Canals with Dedicated Stainless Steel Instruments and DedicatedNickel/Titanium Instruments which was filed on Jan. 3, 2001. Ser. No.09/753,981 is a continuation-in-part of U.S. patent application Ser. No.09/536,821 entitled Endodontic Systems and Methods for the Anatomical,Sectional and Progressive Corono-Apical Preparation of Root Canals WithInstruments Utilizing Stops which was filed on Mar. 27, 2000. Ser.No.09/536,821 is a continuation-in-part of U.S. patent application Ser.No. 09/492,566 entitled Endodontic Systems and Methods for theAnatomical, Sectional and Progressive Corono-Apical Preparation of RootCanals with Minimal Apical Intrusion which was filed on Jan. 27, 2000.Ser. No. 09/492,566 is a continuation-in-part of U.S. patent applicationSer. No. 09/325,035 which was filed on Jun. 3, 1999 and is entitledEndodontic Methods for the Anatomical, Sectional and ProgressiveCorono-Apical Preparation of Root Canals with Three Sets of DedicatedInstruments. Ser. No. 09/325,035 issued as U.S. Pat. No. 6,059,572. Ser.No. 09/325,035 was filed as a continuation-in-part of U.S. patentapplication Ser. No. 09/014,763 which was filed on Jan. 28, 1998 and isentitled Endodontic Methods for Progressively, Sectionally andAnatomically Preparing Root Canals with Specific Instruments for eachSection having Predetermined Working Lengths. Ser. No. 09/014,763 issuedas U.S. Pat. No. 6,045,362. Ser. No. 09/014,763 is acontinuation-in-part of U.S. patent application Ser. No. 08/885,906which was filed on Jun. 30, 1997 and issued as U.S. Pat. No. 5,775,904.Ser. No. 08/885,906 is a continuation of U.S. patent application Ser.No. 08/656,988 which issued as U.S. Pat. No.5,642,998. U.S. Pat.No.5,775,904 and U.S. Pat. No.5,642,998 are both entitled EndodonticInstrument for Rapid Mechanical Widening of the Canal Mouth andSpecification of the First Two-Thirds. Priority of U.S. Pat. No.5,642,998 is based on Italian Patent Application No. RM95A000377 whichwas filed on Jun. 6, 1995. For purposes of disclosure of the presentinvention, each of the foregoing applications is incorporated herein byspecific reference.

BACKGROUND OF THE INVENTION

[0002] 1. The Field of the Invention

[0003] The present invention is related to the field of endodontistry.More particularly, the invention is related to systems and operatingmethods for the preparation of root canals for obturation and thesubsequent obturating of the root canals. The systems and methodsinvolve the use of instruments which are dedicated to preparing apicalportions of root canals for obturation.

[0004] 2. The Relevant Technology

[0005] To preserve a tooth with a pulp that is diseased or ispotentially diseased, it is generally necessary to remove as much of thepulp material as is possible from the pulp canal of the tooth, to shapethe root canal(s) without excessively weakening the root canal walls, toprevent or minimize the presence of bacteria through the use ofirrigants and dressings, and lastly, to clean the walls of the rootcanal(s) by removing the smear layer created during instrumentation ofthe root canal(s). These steps are all done to prepare the root cavityfor sealing or obturation which involves filling the root canal withbiocompatible materials, such as gutta percha, before the pulp cavity issealed, thereby promoting the healing and functional recovery of thetooth. This procedure is referred to as root canal therapy.

[0006] As indicated hereinabove, root canal preparation involves pulpremoval, cleaning of the root canal walls and shaping of the canalwalls. This is typically achieved through a guided procedure with theuse of instruments which are moved either manually, mechanically or bycombinations thereof These instruments are files or bits that areconfigured to bore and/or cut. Mechanical instrumentation can beachieved through the use of endodontic handpieces coupled to instrumentssuch as files. The endodontic handpieces can impart rotational motion toa file, reciprocal motion by alternately rotating a file clockwise andcounterclockwise, sonic movements or ultrasonic movements.

[0007] With regard to operating procedures, there are two basic methodsfrom which all of the canal-preparation techniques can be derived. Thesemethods have been interpreted by various authors in an operationalcontext and also in terms of the instrumentation. The primaryconventional systems and methods for removing pulp material from theroot canal of a tooth are the apico-coronal (step-back) technique andthe corono-apical (crown-down) technique. Although these conventionalcleaning techniques both rely generally on sequential increases in thediameter of instruments inserted into the root canal. The step-backtechnique involves the sequential use of instruments by first insertingan instrument all the way down to the apex of the root canal and thenusing progressively larger and shorter files to clean the root canal. Sothe step-back technique involves cleaning the root canal from the apextoward the crown. The crown-down technique uses a set of files that areinserted sequentially further and further into the root canal untilreaching the apex and then instrumenting along the entire length of theroot canal after the apex has been reached. Each technique has its ownunique benefits and disadvantages.

[0008] Regardless of which system is utilized, they both rely on ISOdimensions in terms of length, tip diameter and taper. In accordancewith ISO, 0.20 is the standard taper of instruments used in cleaning theapical portion. After the apical portion has been cleaned, then one ormore soft, resilient, needle-like inserts known as gutta percha pointsare inserted in each root canal branch in order to at least partiallyseal and fill the root canal. These gutta percha points are alsomanufactured in accordance with ISO and have a 0.20 taper like theinstruments used to shape the apical portion.

[0009] The term “gutta percha” refers to a rubbery material derived fromnatural rubber, typically blended with zinc oxide. This particularrubbery material is preferred because it is compressible, flexible andrelatively soft so that it can be used to fill voids within the exposedroot canal. The gutta percha points are typically impregnated with othermaterials such as radiopaque solids, zinc oxide, for its medicinalproperties, and other passive or active ingredients as desired.

[0010] The gutta percha point or cone is used to seal the apex of theroot canal. In order to ensure that the apex has been adequately sealed,a “tug back” seal is formed. That is, the gutta percha cone is firstinserted and then removed. If it can be removed with little or no force,the gutta percha point is trimmed to yield a larger diameter tip andreinserted into the ape. This process is repeated until there is “tugback,” thus indicating that the fit between the gutta percha point andthe apex is sufficiently tight to adequately seal the apex. However, insome instances the “tug back” may occur above the apex. When thisoccurs, the apex is not sealed and fluids may enter into the root canalthrough the apex. This can lead to discomfort and in some instances tofailure of the procedure.

[0011] To overcome this problem, what is needed in the art of endodonticprocedures are methods and system which improve the ability of anendodontic point such as a gutta percha point to seal a root canal atthe apex of the root canal.

[0012] It would be an additional improvement in the art to providemethods and systems that result in a more thorough cleaning of theapical portion of the root canal to ensure that the “tug back” does notoccur during the procedure before the apex has been reached.

SUMMARY AND OBJECTS OF THE INVENTION

[0013] An object of the present invention is to provide, methods andsystems which improve the ability of an endodontic point such as a guttapercha point to seal a root canal at the apex of the root canal.

[0014] It is also an object of the present invention to provide methodsand systems that provide for a more thorough cleaning of the apicalportion of the root canal to ensure that the “tug back” does not occurduring the procedure before the apex has been reached.

[0015] An additional object of the present invention is to providemethods and systems which enable the apical portion to be cleaned withfiles having tapers larger than standard instruments having an ISO taperafter the portion above the apical portion has been cleaned and shaped.

[0016] Finally, it is an object of the present invention is to providemethods and systems that shape the apical portion of a root canal in amanner that enables a narrow cannula to reach as far as need to deliveradhesive resins for use in filling and/or sealing the root after thegutta percha point has been positioned in the root canal.

[0017] Some of the features of the invention which enable these objectsto be achieved are summarized hereinbelow.

[0018] An apical portion instrument is provided that enables an apicalportion of a root canal to be cleaned in a manner than enables anendodontic point, such as a gutta percha point to be easily received inthe apical portion of the root canal to seal the apex. It is optimal toutilize a set of instruments. Each instrument in the set has a file thatis long enough to extend to the apex of the root canal. At least one ofthe files in the set of instruments has an abrading portion with a taperthat is greater than 0.20. Since conventional gutta percha points have ataper of about 0.20, like conventional instruments used to clean theapical portion of root canals, cleaning the apical portion with anabrading portion of a file that has a taper that is greater than 0.20enables the gutta percha point to encounter significantly less obstaclesor resistance when compared with prior art methodologies.

[0019] All of the instruments may have files with abrading portions thathave the same taper, such as about 0.25. However, as long as the lastfile used to clean the apical portion is larger than 0.20 then theothers can have any suitable taper. In one embodiment, several of thesmaller files have abrading portions with tapers that are 0.20 while thelarger files have abrading portions with tapers that are greater than0.20.

[0020] The instruments may be used in accordance with any methodology.However, the apical portion cleaning instruments are preferably usedafter the operative middle portion and the operative coronal portionhave been cleaned in conformance with their anatomical shapes. In someinstances, it may be necessary to improve access into the apical portionsuch that an irrigation needle can be deployed to deliver irrigants tothe apical portion after the operative middle portion and the operativecoronal portion have been cleaned.

[0021] These and other objects and features of the present inventionwill become more fully apparent from the following description andappended claims, or may be learned by the practice of the invention asset forth hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order that the manner in which the above-recited and otheradvantages and objects of the invention are obtained, a more particulardescription of the invention briefly described above will be rendered byreference to a specific embodiment thereof which is illustrated in theappended drawings. Understanding that these drawings depict only atypical embodiment of the invention and are not therefore to beconsidered to be limiting of its scope, the invention will be describedand explained with additional specificity and detail through the use ofthe accompanying drawings listed hereinbelow.

[0023]FIG. 1 is a view of a system of endodontic tools including a firstset of instruments for cleaning the operative middle portion of anoperative root canal, a second set of instruments for improving theaccess into the apical root portion and a third set of instruments forcleaning the apical root portion.

[0024] FIGS. 2A-2B show embodiments of endodontic files operated by adriver, such as an electric motor or an air turbine, with lengths thatenable the portions of the root canal above the apical portion to becleaned.

[0025]FIG. 3 is a longitudinal cross-sectional view of a tooth with afile inserted into a root canal having a length that is sufficient toreach the apex.

[0026]FIG. 4 is a cross sectional view of the tooth 240 showing a rootcanal with a gutta percha cone inserted into the apex so as to seal theapex and provide a fluid-tight seal.

[0027]FIG. 5 is a cross sectional view of the tooth 240 in which a smalldiameter cannula device has been inserted within the root canal for thepurpose of filling the root canal with an endodontic sealing or fillingresin.

[0028]FIG. 6 is a cross sectional view of the tooth 240 after the rootcanal has been filled with an endodontic sealing or filling resin.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0029] The present invention relates to a system of endodontic fileinstruments utilized to clean the apical portion of a root canal. Theseapical portion instruments have tapers that are larger than conventionalISO tapers. As a result, an endodontic point used to fill the root canalafter it has been prepared such as a gutta percha point is more likelyto indicate that the fit between the gutta percha point and the rootcanal is at the apex than at some point above the apex. Moreparticularly, the “tug back” or engagement of the distal end of thegutta percha point with the root canal walls occurs at the apex.

[0030] The file instruments used to clean apical portions of root canalsthat have tapers that are greater than the taper standard set by theInternational Organization for Standardization (ISO) may be designed, inaccordance with the present invention, for use with any methodology usedto clean root canals in preparation for obturating the root canal with amaterial such as a gutta percha point. For example, the file instrumentsmay be used in a step-back methodology or a crown-down methodology aslong as the apical portion is cleaned with an instrument that has agreater taper than the gutta percha point that is subsequently insertedduring the obturation process. However, the files instruments arepreferably utilized in accordance with a unique methodology explainedbelow in detail. Also discussed below, are methods and compositions forfilling and sealing a root canal after placement of a single guttapercha point in a root canal that has been prepared and cleaned with ataper that is greater than that of the gutta percha point.

[0031] As discussed above, conventional files used in cleaning apicalportions of root canals have a taper that is 0.2 in conformance with ISOspecifications. Similarly, gutta percha points that are inserted intothe root canal once it has been fully cleaned have a taper that is also0.2 in conformance with ISO standards. It has been found that use of afile instrument having an abrading portion with a taper that is greaterthan 0.2 or a set of instruments designed for use in series such that atleast the last instrument in the set has an abrading portion with ataper that is greater than 0.2 is beneficially utilized with a guttapercha point that has a taper of 0.2. Any file instrument with anabrading portion that has a taper that is sufficiently greater than 0.2to enable gutta percha points having a taper of 0.2 to be easilyinserted to the apex with out prematurely binding is within the scope ofthe present invention. The taper of such abrading portions may be only0.225, however, the taper of the abrading portion is preferably at leastabout 0.25 in order to ensure that the taper of the apical portion ofthe root canal is greater along its entire length than the taper of thegutta percha point inserted into the root canal. Accordingly, the taperof the abrading portion of the file of the apical portion instrument ispreferably at least about 0.225, more preferably greater than about0.225 and most preferably at least about 0.25.

[0032] As indicated above, any instrument is within the scope of thepresent invention that has an abrading portion with a taper that isgreater than that of 0.2 or of the gutta percha point inserted into theroot canal. Also such instruments can be used in accordance with anymethodology. However, the instruments are preferably part of a systemthat involves the progressive cleaning of sections of the root canalfrom the crown to the apex by first cleaning the portion above theapical portion of the root canal and then cleaning the apical portion.This methodology is disclosed in numerous patents and patentapplications filed on behalf of Francesco Riitano and owned by UltradentProducts, Inc. of South Jordan, Utah. As explained in detail below, thismethodology known as EndoEze® AET™ (Anatomic Endodontic Technology)system owned by Ultradent Products, Inc. enables the instruments to beused in anatomical conformance with the shape of the root canal. U.S.patents that relate to this methodology include U.S. Pat. No. 6,045,362and U.S. Pat. No. 6,059,572. U.S. applications related to thistechnology include U.S. patent application Ser. Nos. 09/492,566;09/536,821; 09/753,981. Each of the foregoing patents and applicationsis herein incorporated herein as noted above.

[0033] The EndoEze® EndoEze® AET™ (Anatomic Endodontic Technology) ofUltradent Products, Inc. referenced above involves the use of distinctinstruments as are shown in FIG. 1 to clean and shape the anatomicalroot canal in different phases such that the root canal is cleanedprogressively and sectionally. The instrument(s) associated with eachphase have been designed specifically for that particular phase andaccordingly have unique customized characteristics and features. Thesystem of instruments shown in FIG. 1 are described hereinbelow in moredetail after explaining the procedures for completing each phase withthe different instruments shown in FIG. 1.

[0034] The system of instruments shown in FIG. 1 includes three distinctsets. To appreciate the nomenclature used for these sets, reference ismade to FIGS. 2A-2B and 3 which depict a molar 240 in various stages ofthe root canal cleaning procedure. FIG. 2A depicts a root canal 252 abeing cleaned after the overhanging portions of enamel 242 and dentin244 have been removed to provide access into pulp chamber 246 and afterthe pulp material 250 has been removed from pulp chamber 246. Thesections of the operative root canal being cleaned in FIGS. 2A-2Binclude the operative coronal portion 260 and the operative middleportion 262. The apical portion 264 is shown being cleaned in FIG. 3.The operative coronal portion 260 essentially includes the access cavitywalls down to the floor 256 of pulp chamber 246. The operative middleportion 262 is the upper portion of the anatomical root canal while theapical portion 263 is the lower portion of the anatomical root canal Atypical apical portion 264 is the last or bottom 3 mm of the anatomicalroot canal. For example, the apical portion 264 of root canal 252 aextends 3 mm above apex 254 a.

[0035] The three distinct set of instruments are namely a set ofinstruments for cleaning the operative middle portion identified asoperative middle portion set 10; an optional set of instruments used toimprove access into the apical root portion identified as optional set40; and a set of instruments for removing and cleaning essentially allpulp material from the apical root portion that is identified as apicalportion set 70. FIGS. 2A-2B depict file 14 a of instrument 10 a fromoperative middle portion set 10 being used to clean to clean the pulpmaterial from the root canal operative middle portion 262 of tooth 240.Once operative middle portion 262 has been cleaned, then the apicalportion 264 is cleaned as shown in FIG. 3 with one of the instrumentsfrom apical portion set 70 such as 70 d. In some instances, it isnecessary to use an instrument from optional set 40 before cleaning theapical portion in order to widen the transition from the operativemiddle portion 262 to apical portion 264.

[0036] The features of each set are provided below in detail in theExample of the Preferred Embodiment. It should be understood, however,that each instrument has a file with a top end extending from a handle.File instruments can also be manufactured that are just a file without ahandle. File instrument 10 a has a file 14 a extending from handle 12 a.File 14 a has a shank portion 16 a and tines or an abrading portion 19a. The abrading portion extends from tip 18 a to shank portion 16 a. Thefeatures of the other files are similarly numbered.

[0037] Before utilizing an instrument from set 10, the practitionerfirst identifies the combined length of the operative middle portion 262and the operative coronal portion 260. The practitioner then selects afile instrument or a set of file instruments such as set 10 with a filelength corresponding to the combined length of the operative middleportion length and the operative coronal portion. After removing theoverhanging enamel 242 and dentin 244 with any suitable instrument, file14 a of file instrument 10 a is then inserted into root canal 252, asshown in FIG. 2A, down through operative middle portion 262 withoutextending substantially into apical portion 264. Each file 14 of eachfile instrument in the set of instruments 10 shown in FIG. 1 has alength that is only sufficient to enable the file to contact theoperative middle portion and the operative coronal portion of the rootcanal. Accordingly, a file instrument such as file instrument 10 a or aset of file instruments such as 10 comprises a first endodonticinstrument means for anatomically removing and anatomically cleaningessentially all pulp material from the operative middle portion withoutsignificantly removing pulp material from the apical root portion.

[0038] The file length of files 14 a-b enables a practitioner toaggressively clean the operative middle portion without worrying thatthe instrument will overly thin the root canal, perforate the apex orthat cleaning will cause extrusion of material through the apex. Anotherbenefit of cleaning the operative middle portion 262 first is that theapical portion 264 is then generally more accessible and easily cleaned.Additionally, since instruments are selected for use in cleaning theoperative middle portion 262 which have files lengths that do not permitentry into the apical portion 264, the likelihood of jamming or breakinga tip of an instrument while working in the confined space of the apicalportion 262 is prevented.

[0039] By instrumenting in the operative middle portion 262 and theoperative coronal portion 260 before the cleaning the apical portion,the practitioner can use an instrument according to the presentinvention that is relatively flexible compared to the conventionalinstruments. As shown in FIG. 2B, which is a cross-sectional view takenalong cutting line 2B--2B of tooth 240 in FIG. 2A, file 14 a of fileinstrument 10 a is sufficiently flexible to be flexed against anysurface of operative middle portion 262 or operative coronal portion 260and yet is sufficiently rigid to remain flexed against the surfaceduring a cleaning motion such as a longitudinal motion, a rotationalmotion or a reciprocating rotational motion. The file is alsosufficiently resilient that substantial deformation of the file does notoccur due to the forces experienced during cleaning of the pulp materialfrom the root canal.

[0040] File instrument 10 a is shown in FIGS. 2A-2B being moved in alongitudinal movement or up and down movement as well as being rotatedwhile file 14 a is flexed or arched to urge the file against the rootcanal surfaces. As shown, the configuration and mechanical properties ofthe files used to clean the operative middle portion 262, and preferablythe operative coronal portion as well 260, enable a practitioner to movethe files around the perimeter or from side to side to contact theperimeter. Such movements enable the file to follow the contours of theroot canal. Further, since the file is moved around the perimeter, thefile has more than one center of motion during cleaning of the operativemiddle portion of the root canal, such as a pivot point or center ofrotation, as the tip of the file or at least a part of the abradingportion does not generally remain primarily in one position. Stainlesssteel is the preferred material for forming the files of the instrumentsin set 10.

[0041] Due mainly to the configuration and mechanical properties of thefiles, the contours of the operative coronal portion and the operativemiddle portion can be used during their cleaning by a practitioner as aguide for the movements of the files as the files are pushed against thesurfaces of the root canal and simultaneously moved around the perimeteror periphery of the root canal until the practitioner has reached thebeginning location of the cleaning and shaping process. By adapting tothe perimetrical or perimetral anatomy of the root canal, the entireperimeter or substantially all of the perimeter is contacted and cleanedalong the length of the perimeter without substantially altering theconfiguration of the perimetrical anatomy. For example, in root canalsthat are primarily noncircular, the files can be urged along one sideand then along the next side wall in a manner such that the resultingcleaned and shaped root canal is generally widened but still primarilynoncircular. In other words, there is essentially no borehole thatobviously corresponds to the shape of the file. Also since aperimetrical anatomy that was primarily tubular or laminar will beenlarged but will still be primarily tubular or laminar, the tooth isless likely to be weakened as compared with prior art methodologies.

[0042] Due to the ability to move the file as discussed, the anatomy ofthe root canal remains substantially unaltered despite the cleaning ofessentially all pulp material from the operative middle portion. Theunderstanding that the final anatomy is guided by the shape of theoriginal anatomy enables a practitioner to more confidently urge a filesuch as file 14 a against all surfaces of root canal 252 andaggressively clean all of the surfaces of operative middle portion ofthe root canal since the likelihood of overly thinning the root canal orcausing lateral perforations is diminished.

[0043] Another advantage of the configuration and mechanical propertiesof operative middle portion instruments, such as file 14 a shown inFIGS. 2A-2B, is that the file can simultaneously abrade both operativecoronal portion 260 and operative middle portion 262. The files cansimultaneously abrade both portions as each file has an abrading portionalong the entire length of the file. A primary benefit of simultaneouslyabrading both portions is the ability to further straighten theoperative coronal portion 260 while cleaning the operative middleportion 262.

[0044] Use of files in the operative middle portion which have anabrading portion along their entire length or along substantially all oftheir length such as abrading portions 19 a-d is in contrast to filesformed in accordance with ISO standardization. ISO standardized fileshave abrading portions of up to 16 mm and the remainder of the file is asmooth shank. Since such files are inserted down to the apex, it isgenerally not possible to abrade any portion beyond the anatomical rootcanal. Additionally, since such ISO standardized files frequently failto remove interferences extending from the access or root chamber abovethe anatomical root canal, the instrument that is manufactured withconventional materials must bend around the interferences, therebyfurther increasing the likelihood of wall perforations, overthining andfailing to clean significant portions of the canal. It especiallyincreases the likelihood of iatrogenic modifications resulting from thetip of the file.

[0045] File instrument 10 a is preferably used in conjunction with anendodontic handpiece designed for movement of endodontic fileinstruments as shown in FIGS. 2A-2B at 100. The endodontic handpiece 100and file 10 a are drawn in phantom lines to represent the ability of thefile to be moved and flexed as root canal 252 a is cleaned. Fileinstrument 10 a can be continuously rotated in one direction only orfile instrument 10 a can be rotated in a reciprocating motion such thatfile instrument 10 a rotates for example, clockwise for half of arevolution and then counterclockwise for half a revolution. Areciprocating motion is preferred as such motion enables the file toalternately engage material 250 and the walls of the operative middleportion of the root canal in a manner that removes material 250 and tothen rotate in the opposite direction such that the file lessaggressively engages material 250 and the operative middle portionwalls, depending on the file design. Accordingly, rotating fileinstrument 10 a in a reciprocating motion minimizes breakage of file 14a when file 14 a encounters a surface that prevents rotation of fileinstrument 10 a in a direction that enables cleaning and removal ofmaterial 250. File instrument 10 a can also be vibrated or manipulatedby hand. Hand milling is, however, more difficult and time consuming.The optional stop 140 shown being utilized is generally not necessarysince the file length can be selected to correspond closely with thecombined length of the operative coronal portion and the operativemiddle portion.

[0046] As indicated above, it may be necessary in some circumstances toimprove the access into the apical root portion before cleaning theapical root portion of the root canal. More particularly, it may bebeneficial or necessary to widen the tract of the root canal to provideaccess for thin irrigation needles. This may be achieved by widening thetransition between the operative middle portion 262 and the apicalportion 264 or by widening the entire apical portion such that a thinirrigation needle can access the apical portion as needed. Thinirrigation needles typically have a diameter no smaller than about 0.30mm so it may be necessary to increase the diameter of portions of theroot canal up to about 0.35 mm or even up to about 0.40 mm, particularlywithin the region of the boundary between the operative middle portionand the apical root portion. Note that the diameter need only beslightly larger than a thin irrigation needle in order to provideadequate access. Improving access into the apical portion not onlyenables such irrigation needles to move as needed, it also reduces thelikelihood that the thin irrigation needes will be blocked. AlthoughFIG. 3 depicts file 74 d inserted into apical portion 264 of root canal252 a cleaning the apical portion, use of instruments 40 a or 40 b ofoptional set 40 is achieved in essentially the same fashion. Whenutilized to widen the access into the apical root portion of a rootcanal, file 40 a is first introduced followed sequentially by file 40 b.A file instrument such as file instrument 40 a or a set of fileinstruments such as 40 a and 40 b comprises a second endodonticinstrument means for improving access into the apical root portion afterthe pulp material has been essentially removed from the operative middleportion by the first endodontic instrument means.

[0047] Set 70 is shown with twelve instruments. However, in use only 1-3instruments are typically utilized. If a file is inserted and it isapparent to the practitioner that the file is not engaging the walls ofthe root canal in the apical portion, then a larger file is inserted.While instrumenting the root canal with only this instrument may besufficient, it is often necessary to utilize one or two additionalinstruments with successively larger files. So for example, if file 70 bor 70 c is first introduced into the apical root portion then it isfollowed by then next larger file such as 70 c or 70 d.

[0048] The dimensions of the files 70 a-1 are provided below in detailin the Example of the Preferred Embodiment. Note that all of theabrading portions 79 a-1 may have the same taper or a set may includefiles with abrading portions having different tapers. However, the lastfile used to instrument in the apical portion has a taper that isgreater than the conventional ISO taper of 0.2 to enable the guttapercha points to be easily inserted. For example, as described in detailin the Example of the Preferred Embodiment, the first several files mayhave abrading portions with a conventional ISO taper of 0.2 while theremainder have a taper of 0.25. Alternatively, all of the files may haveabrading portions with a taper that is about 0.25 or greater than about0.25.

[0049] Use of a file with an abrading portion having a taper that isgreater than 0.2 may be considered to be slightly more aggressive thanuse of a file with an abrading portion having a taper that is 0.2. Whileit is safe to utilize files with abrading portions having tapers thatare greater than 0.2 in the apical portion of a root canal in accordancewith conventional methodologies such as the step-back methodology or thecrown-down methodology, it is preferred to use such apical files afterthe operative middle portion 262 has been cleaned, as described above.

[0050] The apical portion, as discussed above, is the location in theroot canal of most complications that occur during a root canal cleaningprocedure. The greatest likelihood for the occurrence of complicationssuch as over thinning of root canal walls, perforation or extrusion ofmaterial from the canal is in the apical portion. The apical portion isthe most likely site for such complications as apical portions are morecomplex and delicate compared to the operative middle portions of teeth.Since such complications are most likely to occur in the apical portion,it is highly beneficial to make it easier to clean the apical portion byfirst cleaning the operative middle portion.

[0051] Additionally, it is highly beneficial to have the materialremoved from the operative middle portion in order to minimize theamount of material that can come out of the root canal to causeproblems. Since the majority of bacteria in an infected root canal istypically located in the operative middle portion, removal of pulpmaterial 250 from operative middle portion 262 removes the majority ofbacteria in the pulp canal. Not only is the greatest volume of bacteriain the operative middle portion but it is also believed that theconcentration is greater in the operative middle portion. Since acertain minimum threshold must generally be reached for complications toarise due to microbial presence in a root canal, removal of the pulpmaterial in the operative middle portion before cleaning the apicalportion significantly reduces the likelihood of complications such asexposing the surrounding tissue to bacteria due to overly thinning theroot canal, perforation or extrusion of material from the canal. Forexample, in the event of an apical extrusion far less septic materialmay be expressed during instrumentation in accordance with presentmethodology than if the apical extrusion occurred as a result ofcleaning in accordance with conventional methods wherein files areinserted to the apical portion before cleaning the operative middleportion. As a result, removal of the majority of bacteria beforecleaning the apical portion increases the likelihood of successful rootcanal therapy in several ways compared with conventional methods. Moreparticularly, since the aggressive cleaning motions do not occur in theapical portion, the likelihood of complications is decreased and if acomplication does occur in the apical portion it is less likely toresult in failure of the procedure.

[0052] So while use of a file with an abrading portion having a taperthat is greater than 0.2 may be considered to be more aggressive thanuse of a file with an abrading portion having a taper that is 0.2, whenutilized after the operative middle portion 262 has been cleaned thereis little if any increased risk of failure due to complications arisingfrom the use of a larger taper apical file. Further, since the largertaper enables the gutta percha to be positioned in the apex with greatercertainty that the apical foramen is closed, the use of the presentinvention decreases the risk of failure due to complications such asinfections.

[0053] Each file instrument 70 a-1 comprises a handle 72 a-1 connectedto a file 74 a-1. Each file 74 has a top end where the file joins handle72. Each file terminates at a tip 78 a-1 located opposite the top end ofthe file. Tips 78 a-1 can have any configuration, however, tips 78 a-1preferably have minimal cutting capability to decrease the likelihood ofledging such as the tips shown in FIGS. 8-9. A file instrument such asfile instrument 70 a or a set of file instruments such as 70 a-1comprises a third endodontic instrument means for removing and cleaningessentially all remaining pulp material from the apical root portionafter the pulp material has been essentially removed from the operativemiddle portion.

[0054] When cleaning the apical portion 264 as shown in FIG. 3, theapical root portion file instruments are generally moved in a differentpattern compared to the operative middle portion file instruments dueprimarily to the different perimeter anatomies of the two portions. Aroot canal generally becomes more cylindrical towards the apical portionsuch that a root canal with a perimeter anatomy that is essentiallyelliptical in shape within the operative middle portion tapers to anessentially cylindrically shaped perimeter anatomy within the apicalportion.

[0055] An elliptical perimeter anatomy typically requires that thepractitioner move the file around the perimeter and/or flex the rotatingfile against the surfaces or walls in a milling motion such that the tipis moved to many locations around the perimeter. Due to the morecylindrical anatomy of an apical root portion, it becomes much lessnecessary, and virtually impossible to flex a rotating file in a millingmotion. It is generally adequate to merely rotate the file within theapical root portion and/or move the file in a longitudinal motion. Morespecifically, after the file reaches the apex or approximately reachesthe apex, the file is preferably moved upward while simultaneously beingrotated, and it is withdrawn in order to be cleaned before beingreintroduced. Since the instruments used to clean the apical portion andto improve the access into the apical portion are typically moved byhand, they have a handle adapted for such use as shown at 42 a-b and 72a-721 while the instruments used to clean the operative middle portionhave handles 12 a-b adapted for use with an endodontic handpiece. Thefile instruments of the present invention can, however, be utilized withany suitable handle configuration. All of the handles disclosed hereinare examples of end means for grasping and operatively moving a file inan abrasive action.

[0056] Since an apical portion file is generally not moved around theperimeter as in cleaning the operative middle portion, the center ofmotion, such as the center of rotation, of the file generallycorresponds with the center of the root canal. In contrast, the centerof motion during cleaning of the operative middle portion is at variouslocations as the file is moved around the root canal.

[0057] The files used to clean the apical root portion can be designedfor primarily longitudinal movement, rotational movement or combinationsthereof Since it is generally not necessary to flex a file when cleaningthe apical root portion as the apical root portion is typically moreround than other sections of a root canal, apical root portion filesneed not necessarily have the same properties as the operative middleportion files in terms of flexibility, rigidity and resilience. Thefiles used to clean the apical portion are, however, preferablysufficiently flexible to adjust to the anatomy or structure of a rootcanal in a manner that enables the tip of the file to reach the apex.The files also preferably have sufficient rigidity to apply pressureagainst the walls or surfaces of the root canal as the abrading portionof the file is urged against the walls of the root canal andsimultaneously moved in a cleaning motion even after the file has movedthroughout the length of the root canal. Additionally, a file configuredfor use in an apical root portion preferably has adequate resilience toavoid being substantially deformed as the file passes through a rootcanal and also as the abrading portion is applied against the walls ofthe root canal.

[0058] The apical portion cleaning instruments are preferably moreflexible than the instruments used to clean the operative coronalportion and the operative middle portion since the apical portions tendto be more curved. While stainless steel may be utilized, the files arepreferably formed formed from nickel/titanium or a stainless steel alloysuch as a precipitation hardenable stainless steel, particularly 17-4PHstainless steel that has not been aged or subjected to heat treatment.While files can be formed from these same metals that are utilized inthe operative coronal portion and the operative middle portion, suchmetals are particularly suited for use in the apical portion as suchmetals provide optimal flexibility. The instruments used to optionallyimprove the access into the apical portion may also be formed from anyof these metals.

[0059] The shapes and dimensions of the embodiments of endodontic fileinstruments provided herein are merely illustrative, but not limiting,of the variety of endodontic file instruments that are manufacturedaccording to the present invention. Files used to clean the apicalportion may have any suitable transverse cross-sectional shape. Anyconventional technique may be used to form the files such as twisting aprecursor cylindrical rod or blank having three or four sides, cuttinglands in a precursor blank or cylindrical rod, abrading the precursorblank or rod to impart a roughened surface, or appropriately machining aprecursor blank to form a knurled surface. As a result, the abradingportion may appear like conventional K-files or Hedstrom-type files. Thefiles preferably, however, are configured in a manner such that thepotential for breakage is minimized. For example, a file with a squarecross-section may be preferred over a triangular cross-section as thefile with a square cross-section has a greater mass and is accordinglyless likely to break. Additionally, a file configured with tines orextensions having wide angles are generally preferred over those withnarrow angles. However, the preferred tine configuration dependsprimarily on the particular use as in some instances it is desirable toaggressively cut while in others the root can be passively cut. When itis more desirable to aggressively cut, it may be preferred for exampleto utilize a file with relatively narrow tines. All of the files incombination with their respective abrading portions disclosed herein areexamples of means for removing and cleaning of pulp material as the fileinstrument is operatively moved. Additionally, each abrading portiondisclosed herein is an example of a means for abrading a root canal.

[0060] Reference is now made to FIGS. 4-6. FIG. 4 depicts tooth 240 withgutta percha cones 300 a-b inserted into each root canal 252 a-b andinto each opening of apices 254 a-b in order to seal the apex 252 a-b ofeach root canal 252 a-b to prevent flow of sealing material into thesurrounding bone tissue.

[0061] As discussed above, in order to ensure that each gutta perchacone 300 a-b forms a reliable seal within the respective apices 252 a-b,a procedure involving “tug back” is performed In this procedure, thegutta percha cone is inserted and removed, sometimes more than one time,to determine how much force is needed to remove the gutta percha cone.If it can be removed with little or no force, there is insufficient tugback, and the gutta percha point is trimmed to yield a larger diametertip and is reinserted into the apex. This process is repeated untilthere is sufficient tug back, or resistance, felt by the dentist ordental practitioner. One of ordinary skill in the art of endodonticswill know when there is sufficient tug back to confirm an adequate sealof the apex 252 a-b by the gutta percha cones 300 a-b. Sufficient tugback indicates that the fit between the gutta percha cone and the apexis sufficiently tight to adequately seal the apex and prevent flow ofsealing or filling material therethrough into the surrounding bonetissue. As discussed above, the apical portion has been cleaned by thefile of an instrument with an abrading portion having a taper that isgreater than 0.20 while the taper of the gutta percha cone or points 300a-b has a taper of 0.20 in accordance with ISO. Accordingly, guttapercha cones 300 a-b easily extend to an occlude the foramina of theapices as shown.

[0062] In addition to the root canals 252 a, there are also numerouslateral canals (not shown) that extend from the root canals 252 a-b andprovide communication between each root canal 252 a-b and thesurrounding periodontal tissue of the lower portion of the tooth 240.The lateral canals 253 a-b are particularly difficult to seal usingconventional compositions and methods. Inventive compositions andmethods, however, facilitate penetration of resinous sealing or fillingmaterial into the lateral canals 253 a-b. Such compositions and methodsare disclosed in U.S. patent application Ser. No. 09/736,729 entitledEndodontic Sealing Compositions and Methods for Using Such Compositionswhich was filed on Dec. 13, 2000 and was previously incorporated byreference.

[0063] In a preferred method for placing a resinous sealing or fillingmaterial within a root canal, FIG. 5 depicts a syringe tip 400 having anarrow diameter cannula 420 extending from a hub 410 of the syringe tip400 used to insert sealing or filling material into the root canals 252a-b. Due to the narrow opening of the cannula 420, and because typicalsealing or filling materials are often sufficiently viscous that theymay not readily pass through the cannula 26, it is generallyadvantageous for the syringe tip 400 to be attached to a high pressureinjection system (not shown). An example of high pressure injectionsystem is the hydraulic syringes or systems set forth in copending U.S.patent application Ser. No. 09/742,516 entitled Hydraulic Syringe andMethod of Manufacture, filed Dec. 20, 2000. Examples of narrow cannulassized for entry into a root canal are set forth in U.S. Pat. No.6,079,979, which is assigned to Ultradent Products, Inc. For purposes ofdisclosing hydraulic pressurizing systems and cannulas sized to fitwithin a root canal, the foregoing patent application and patent areincorporated herein by specific reference.

[0064] The tip of the cannula 320 is initially placed within one of theroot canals 252 a-b near its respective apex 252 a-b, and then sealingor filling material (not shown) is expressed therefrom into the rootcanal 252 a-b. As the resinous material begins and continues to fill upthe root canal 252 a-b, the cannula 320 is slowly raised or withdrawnfrom the root canal 252 a-b. This manner of filling the root canal 252a-b with resinous material minimizes or eliminates the formation of airpockets or bubbles as the resin is progressively placed within the rootcanal 252 a-b. This procedure greatly improves the ability of the resinto initially purge most or all of the air from within the root canal 252a-b compared to simply dipping a gutta percha point in the resin andstuffing the point into a root canal, as is conventionally done. Notethat due to the width of each root canal, cannula 420 is able to extendwithin the root canals along side each gutta percha point 300 a-b and bewithdrawn as the material is delivered instead of just expressing thematerial in from the top of the root canal.

[0065]FIG. 6 depicts a tooth 240 into which a resinous sealing orfilling material 430 has been successfully placed within the root canals252 a-b, with little or no formation of air pockets. The methodology ofcleaning the operative middle portion before cleaning the apicalportion, positioning a single gutta percha cone or point to seal theroot canal at the apex and then filling the root canal around the guttapercha point is preferred. However, as mentioned above, othermethodologies may be utilized to clean the root canal as long as thelast file used to clean the apical portion has an abrading portion witha taper that is greater than 0.20. Additionally, conventional methodsfor placing gutta percha points into the root canal may also be utilizedafter the apical portion has been cleaned with a is cleaned with a filehaving an abrading portion with a taper that is greater than 0.20. Forexample, a single gutta percha point may be dipped in a filling materialor several gutta percha points may be pushed into the root canal as isconventionally done.

[0066] Preferred compositions for sealing a root canal during anendodontic procedure are disclosed in U.S. patent application Ser. No.09/736,729 which as referenced above is entitled Endodontic SealingCompositions and Methods for Using Such Compositions. After thecomposition is placed around a gutta percha point, then the compositionis allowed to polymerize. The polymerization is generally achieved by achemical initiator in the composition However, a photoinitiator may alsobe utilized in conjunction with a chemical initiator. The chemicalinitiator is selected to enable the composition to polymerize in situafter being placed within the root canal.

EXAMPLES OF THE PREFERRED EMBODIMENTS

[0067] This example describes, in relation to FIG. 1 and FIGS. 2A-3, anexemplary system and method for cleaning a root canal after the rootcanal has been properly accessed. After a tooth has been identified asrequiring root canal therapy, an x-ray image is obtained in order todetermine the state of health of a tooth as well as the structure andanatomical characteristics of the tooth. After all carious tissue hasbeen removed and any old fillings have been infiltrated, a dam isinstalled.

[0068] Before the instruments designed for use in the operative middleportion or the apical portion of the root canal are utilized, the pulpchamber must be properly opened so that adequate access can be gained tothe anatomical root canal. Access is gained by removing the top of thepulp chamber, preferably with an appropriate diamond bur instrument. Thecontents in the pulp chamber are then removed with the aid ofappropriate irrigants. Examples of appropriate irrigants includehydrogen peroxide, primarily for use in the canals of living teeth, orsodium hypochlorite, primarily for the canals in necrotic teeth. Ifdesired a cuspidectomy may be performed.

[0069] It is then preferable to remove or reduce dentinal or enamelprotrusions or irregularities such as dentinal shelves, that may obscureor hinder access of instruments into the operative root canal byrectification of such protrusions with an appropriate instrument whichpreferably utilizes diamonds for abrasion. Rectification enables aninstrument to be inserted in a relatively straight manner though theoperative coronal portion 260 and the operative middle portion 262.Since the apical portion of root canal 252 a is essentially straight,rectification of dentinal shelf 266 above root canal 252 a would alsoenable an instrument to be inserted up to apex 254 a through the apicalportion 264 in an essentially straight configuration. Although, aninstrument would need to flex within the apical portion 264 of rootcanal 252 b due to its curvature, the required flexing is minimized as aresult of the removal of dentinal shelf 266 above root canal 252 b.

[0070] After any necessary rectification, the working length isdetermined for the files used to clean the operative middle portion. Theappropriate working length is determined by radiographically identifyingthe length of the operative root canal and then subtracting 3 mm fromthe length identified from the x-ray image. It is necessary to subtract3 mm from the overall x-ray length in order to compensate for anydistortions in the x-ray image and to avoid interfering with the apicalportion while the operative middle portion is being prepared. Afteridentifying the length of the root canal of a tooth and determining theworking length of the files to be used, instruments can then be selectedwhich have a length such that essentially all pulp material can beanatomically cleaned from the operative middle portion of a root canalwithout significantly removing pulp material from the apical rootportion.

[0071] As discussed above, FIG. 1 depicts three sets of instrumentsidentified at 10, 40 and 70 which are used to prepare a root canal. Asalso discussed above, the sets of instruments identified respectively at10, 40 and 70 are respectively used to clean the operative middleportion, to improve access into the apical portion and to clean theapical root portion.

[0072] Operative Middle Portion Phase and Related Sets of Instruments

[0073] Tables 1A-1D presented hereinbelow describe the dimensions offour different set of instruments which can be used to clean theoperative middle portion in different teeth depending on the particularoperative root canal length. These four sets are preferably sold as partof a kit. Although, the kit includes several sets of instruments, onlyone set of instruments is typically used for cleaning the operativemiddle portion. The practitioner selects from several sets in the kitdepending on the particular length of the operative coronal portion andthe operative middle portion. The instruments in Tables 1A-1D aredesigned to have a working length that is adjustable depending on theplacement of a stop such as stop or the position of the handle withinthe chuck of an endodontic handpiece. Accordingly, the working lengthsfor the instruments in Tables 1A-1D are respectively 15-18 mm, 19-22 mm,23-26 mm, and 27-30 mm TABLE 1A Operative Middle Portion Instruments(15-18 mm) Total Abrading Shank Diameter at Shank Length Portion PortionTip the top of the Portion Abrading Instrument of the File Length LengthDiameter Abrading Diameter Portion Number (L₂ + L₃) (L₂) (L₃) (D₁)Portion (D₃) (D₄) Taper 10a 18 mm 15 mm 3 mm 0.10 mm 0.55 mm 0.50 mm0.025 10b 18 mm 15 mm 3 mm 0.13 mm 0.76 mm 0.70 mm 0.035 10c 18 mm 15 mm3 mm 0.13 mm 1.05 mm 0.90 mm 0.051 10d 18 mm 15 mm 3 mm 0.13 mm 1.17 mm1.00 mm 0.058

[0074] TABLE 1B Operative Middle Portion Instruments (19-22 mm) TotalAbrading Shank Diameter at Shank Length Portion Portion Tip the top ofthe Portion Abrading Instrument of the File Length Length DiameterAbrading Diameter Portion Number (L₂ + L₃) (L₂) (L₃) (D₁) Portion (D₃)(D₄) Taper 10a 22 mm 19 mm 3 mm 0.10 mm 0.65 mm 0.60 mm 0.025 10b 22 mm19 mm 3 mm 0.13 mm 0.90 mm 0.80 mm 0.035 10c 22 mm 19 mm 3 mm 0.13 mm1.14 mm 1.00 mm 0.046 10d 22 mm 19 mm 3 mm 0.13 mm 1.45 mm 1.30 mm 0.060

[0075] TABLE 1C Operative Middle Portion Instruments (23-26 mm) TotalAbrading Shank Diameter at Shank Length Portion Portion Tip the top ofthe Portion Abrading Instrument of the File Length Length DiameterAbrading Diameter Portion Number (L₂ + L₃) (L₂) (L₃) (D₁) Portion (D₃)(D₄) Taper 10a 26 mm 23 mm 3 mm 0.10 mm 0.78 mm 0.70 mm 0.026 10b 26 mm23 mm 3 mm 0.13 mm 0.88 mm 0.80 mm 0.029 10c 26 mm 23 mm 3 mm 0.13 mm1.12 mm 1.00 mm 0.038 10d 26 mm 23 mm 3 mm 0.13 mm 1.43 mm 1.30 mm 0.050

[0076] TABLE 1D Operative Middle Portion Instruments (27-30 mm) TotalAbrading Shank Diameter at Shank Length Portion Portion Tip the top ofthe Portion Abrading Instrument of the File Length Length DiameterAbrading Diameter Portion Number (L₂ + L₃) (L₂) (L₃) (D₁) Portion (D₃)(D₄) Taper 10a 30 mm 27 mm 3 mm 0.10 mm 0.85 mm 0.80 mm 0.025 10b 30 mm27 mm 3 mm 0.13 mm 1.00 mm 0.90 mm 0.029 10c 30 mm 27 mm 3 mm 0.13 mm1.21 mm 1.10 mm 0.036 10d 30 mm 27 mm 3 mm 0.13 mm 1.54 mm 1.40 mm 0.047

[0077] As provided in this example, the instruments having a workinglength of 19-22 mm as presented in Table 1B are selected for use in atooth due to the combined length of the operative coronal portion andthe operative middle portion of the operative root canal which is in therange of 19-22 mm More particularly, the root canal of the tooth isslightly longer than about 25 mm so the full 22 mm of the working lengthis utilized. The set of instruments for cleaning the operative middleportion detailed in Table 1B corresponds with the set of instrumentsshown in FIG. 1 at 10. Since only one set of instruments is used toclean the operative middle portion only one set is shown in FIG. 1 at10.

[0078] When utilized to clean the operative middle portion of a rootcanal, file 10 a is first introduced into the operative middle portionfollowed by file instrument 10 b, 10 c and then 10 d. Note that, asshown in FIG. 1, the diameter at the top of each abrading portion 19 a-dis incrementally greater than the diameter of the top of the abradingportion of the preceding file. Accordingly, the diameter of the top endof each successive file introduced into the operative middle portion isgreater than the diameter of the top end of each preceding file.However, the tip diameter of each file in set of operative middleportion instruments are essentially the same. More particularly, theinstruments in each set detailed above has a first instrument 10 a witha tip diameter of 0.10 mm while the instruments sequentially usedthereafter have a tip diameter of 0.13 mm.

[0079] Since the tip diameters are essentially equal and since thediameter of the top end of each successive file introduced into theoperative middle portion is larger than the diameter of the top end ofthe preceding file, the taper of each successive file in the set islarger than the preceding file as shown in Tables 1A-1D. Each successivefile accordingly has an increased surface area for cleaning the rootcanal. Additionally, as files are inserted into a root canal with largerand larger tapers, the rigidity of the upper half of each successivefile also increases. The increase in rigidity is, however, minimized bymaintaining the tip of each file at about the same diameter. Theflexibility of the lower half remains essentially constant. The rigidityin the upper half is used to remove interferences and to properlyrectify the operative coronal portion 260 and the operative middleportion 262. The consistency in rigidity at the upper half is usefulsince the lateral perimetrical force applied to the handle is primarilytransferred to its upper half or at least the part closest to thehandle, which is the strongest part of the file.

[0080] By properly selecting a combination of factors including thediameters of the files at the top ends and at the tips as well as thematerial used to form the files, the files are designed such that eachfile has sufficient flexibility to be flexed or curved to urge theabrading portion against the surfaces or walls of the root canal andsufficient rigidity to apply pressure against the surfaces of the rootcanal as the abrading portion of the file is urged against the surfacesof the root canal and simultaneously moved in a cleaning motion.Accordingly, a practitioner can move the instrument around the perimeterof the operative middle portion of the root canal using the contours ofthe operative middle portion as a guide for the movement of theinstrument such that the original anatomy is enlarged and notsignificantly altered. The operative middle portion instruments in eachset are preferably formed from stainless steel.

[0081] Apical Portion Widening Phase and Related Sets of Instruments

[0082] Tables 2A-2C detail the dimensions of instruments with filelengths which are respectively 21 mm, 25 mm and 30 mm. In this example,the set presented in Table 2B is selected since a tooth is beinginstrumented with a root canal that is slightly longer than about 25 mm.The set presented in Table 2B is shown in FIG. 1 as set 40. TABLE 2AApical Widening Instruments (21 mm) Total Length Abrad. Square RoundAbrad Square Shank of File Portion Portion Portion Tip Portion PortionPortion Inst. (L₁ +L₃ + Length Length Length Diam. Diam. Diam. Diam. No.L₄) (L₁) (L₄) (L₃) (D₁) (D₂) (D₃) (D₄) Taper 40a 21 mm 5 mm 11 mm 5 mm0.08 mm 0.28 mm 0.30 mm 0.80 mm 0.04 40b 21 mm 5 mm 11 mm 5 mm 0.08 mm0.38 mm 0.40 mm 1.1 mm  0.06

[0083] TABLE 2B Apical Widening Instruments (25 mm) Total Length Abrad.Square Round Abrad Square Shank of File Portion Portion Portion TipPortion Portion Portion Inst. (L₁ +L₃ + Length Length Length Diam. Diam.Diam. Diam. No. L₄) (L₁) (L₄) (L₃) (D₁) (D₂) (D₃) (D₄) Taper 40a 25 mm 5mm 15 mm 5 mm 0.08 mm 0.28 mm 0.30 mm 0.90 mm 0.04 40b 25 mm 5 mm 15 mm5 mm 0.08 mm 0.38 mm 0.40 mm 1.3 mm  0.06

[0084] TABLE 2C Apical Widening Instruments (30 mm) Total Length Abrad.Square Round Abrad Square Shank of File Portion Portion Portion TipPortion Portion Portion Inst. (L₁ +L₃ + Length Length Length Diam. Diam.Diam. Diam. No. L₄) (L₁) (L₄) (L₃) (D₁) (D₂) (D₃) (D₄) Taper 40a 30 mm 5mm 20 mm 5 mm 0.08 mm 0.28 mm 0.30 mm 1.1 mm 0.04 40b 30 mm 5 mm 20 mm 5mm 0.08 mm 0.38 mm 0.40 mm 1.6 mm 0.06

[0085] The files of the instruments in the sets detailed in Tables 2A-2Ceach have three sections including a smooth shank portion, a squareportion and an abrading portion. As indicated above, the set presentedin Table 2B corresponds with set 40 shown in FIG. 1. Note, however, withthe exception of length, the instruments detailed in Table 2A and Table2C would appear just like set 40. Instrument 40 a has a file 44 a withsmooth shank portion 46 a, a square portion 47 a, an abrading portion 49a and a file tip 48 a. As shown, the smooth shank portion 46 a is thetop section of file 44 a and a handle 42 is positioned on shank portion46 a. Smooth shank portion 46 a tapers to square portion 47 a which isbetween shank portion 46 a and abrading portion 49 a.

[0086] The smooth shank portion enables stops be positioned on the fileto adjust the working length of the file. Each smooth shank portion ofeach file has a length of about 5 mm with various diameters. Theinstruments can be used for all operative lengths that are likely to beencountered in clinical practice through the positioning of the stops atthe predetermined lengths. While the instruments can be offered in amore expanded series of millimetrically different lengths, the use ofstops is acceptable, particularly since, these instruments are manuallymoved.

[0087] In each set, the diameter at the top of the square portion ofinstrument number 40 a and instrument number 40 b is respectively 0.30mm and 0.40 mm. The abrading portion is formed by twisting the squaresection so that the abrading portion has a K-file configuration. Theinstruments in each set all have the same tip diameters. The taper ofthe files from the tip (D₁) to the diameter at the top of the squareportion (D₃) remains constant and is respectively 0.04 and 0.06 forinstrument number 40 a and instrument number 40 b in each set.

[0088] Preferably, instrument 40 a is first utilized and then instrument40 b to obtain, in a gradual manner, the desired enlargement of thespecific transition zone between the operative middle portion and theapical portion. This enlargement is also preferably achieved withoutsignificantly changing the diameter of the apical portion of the canal.Accordingly, the tip diameter (D₁) of the various instruments in thisset remains constant while the diameter at the top of the cutting areaor abrading portion (D₂), located 5 mm from the tip, is graduated fromone instrument to the next, reaching a maximum diameter of 0.38 mm. Therest of the shaft, up to the handle, does not have a cutting surface. Tothe extent that these instruments are used to expand the apical portionof the canal, the practitioner should constantly bear in mind theaverage diameters of the canals and the average thicknesses of theparietal walls at the apex.

[0089] Note that the entire length of each file can be configured withan abrading portion, however, each abrading portion 49 a-b preferablyextends from tip 48 a-b along only some of the file. Accordingly, theabrading portion may have any suitable length such as 3 mm or 10 mm;however, the abrading portion in a preferred configuration is about 5 mmor about 6 mm.

[0090] As indicated above, the length of a file such as files 44 a-b ispreferably sufficient such that when the file is inserted into the rootcanal, the tip can at least approximately reach the apex and theabrading portion 49 a-b of the file can improve the access into theapical portion of the root canal. Although files used to improve theaccess into the apical root portion may be long enough to approximatelyreach the apex, the files can be used to improve the access as long asthe files can reach the bottom of the operative middle portion and thetop of the apical root portion. Such file lengths are typically within arange from about 8 mm to about 35 mm, more typically in a range fromabout 14 mm to about 35 mm and most typically in a range from about 12mm to about 33 mm. The length of the abrading portion is generallywithin a range from about 1 mm to about 35 mm, more preferably in arange from about 2 mm to about 16 mm and most preferably in a range fromabout 3 mm to about 6 mm. The abrading portion is preferably long enoughso that the entire apical portion can be abraded as well as at least thebottom of the operative middle portion.

[0091] In a set of instruments used to improve the access into an apicalroot portion, the file tips of the instruments preferably all have aboutthe same diameter as shown in Tables 2A-2C and in FIG. 1 at 48 a-b. Thediameter of the tips may range from about 0.06 mm to about 1 mm however,the tips preferably have a diameter of about 0.08 mm. In a lesspreferred embodiment, the tip diameter of each file may also increasesequentially.

[0092] As shown in Tables 2A-2C and in FIG. 1, the diameter of theabrading portions 49 a-b increases from the tips 48 a-b towards the topof the abrading portions. The diameter of the abrading portion at thetop may range from about 0.1 mm to about 0.4 mm and is more preferablyin a range from about 0.2 mm to about 0.4 mm. Each successive file hasan abrading portion, 49 a-49 b which is successively larger in diameterat the top of the abrading portion than the abrading portion of thepreceding file. Accordingly, a set may have files with abrading portionshaving the following respective top diameters: about 0.2 mm, about 0.25mm, about 0.3 mm and about 0.35 mm. Each abrading portion in such a sethas a different taper. Note that the taper of the smooth or shankportions above the abrading portions also increases sequentially,however, the taper may also remain essentially the same.

[0093] Apical Portion Cleaning Phase and Related Sets of Instruments

[0094] Again sets of instruments are provided with each set having adifferent length. Three sets of instruments are described hereinbelowwhich are designed for removing and cleaning essentially all pulpmaterial from the apical root portion after access into the apical rootportion has been improved by a set of instruments such as set 40detailed in Table 2B. In some instances, the instruments described inthis example can also be used to clean the pulp material from the rootcanal immediately after the operative middle portion has been cleaned bya set of instruments such as the sets presented in Table 1B.

[0095] Tables 3A-3C detail the dimensions of instruments with filelengths which are respectively 21 mm, 25 mm and 30 mm. However, pleasenote that only instruments from Table 3B are used in the tooth beingcleaned in this example. The set of instruments detailed in Table 3B areshown in FIG. 1 as set 70. Set 70 includes instruments 70 a-1 whichrespectively correspond with instruments 70 a-1 in the set presented inTable 3B.

[0096] The instruments in set 70 have a similar appearance as theinstruments in set 40. Instruments 70 a-1 have a handle 72 opposite afile 74. Each file 74 has a smooth shank portion 76, a square portion77, an abrading portion 79 and a file tip 78. The sets of instrumentspresented in Table 3A and 3C have a similar appearance to instrumentsdetailed in Table 3B and shown at 70, however, the files have differentlengths. The taper of the files from the tip (D₁) to the diameter at thetop of the square portion (D₃) is provided in each table. TABLE 3AApical Cleaning Instruments (21 mm) Total Length Abrad. Square RoundAbrad Square Shank of File Portion Portion Portion Tip Portion PortionPortion Inst. (L₁ +L₃ + Length Length Length Diam. Diam. Diam. Diam. No.L₄) (L₁) (L₄) (L₃) (D₁) (D₂) (D₃) (D₄) Taper 70a 21 mm 5 mm 11 mm 5 mm0.10 mm 0.20 mm  0.42 mm 0.50 mm 0.02  70b 21 mm 5 mm 11 mm 5 mm 0.15 mm0.25 mm  0.47 mm 0.50 mm 0.02  70c 21 mm 5 mm 11 mm 5 mm 0.20 mm 0.30mm  0.52 mm 0.60 mm 0.02  70d 21 mm 5 mm 11 mm 5 mm 0.25 mm 0.375 mm0.65 mm 0.70 mm 0.025 70e 21 mm 5 mm 11 mm 5 mm 0.30 mm 0.425 mm 0.70 mm0.70 mm 0.025 70f 21 mm 5 mm 11 mm 5 mm 0.35 mm 0.475 mm 0.75 mm 0.80 mm0.025 70g 21 mm 5 mm 11 mm 5 mm 0.40 mm 0.525 mm 0.80 mm 0.80 mm 0.02570h 21 mm 5 mm 11 mm 5 mm 0.50 mm 0.625 mm 0.90 mm 0.90 mm 0.025 70i 21mm 5 mm 11 mm 5 mm 0.60 mm 0.725 mm 1.0 mm  1.0 mm  0.025 70j 21 mm 5 mm11 mm 5 mm 0.70 mm 0.825 mm 1.1 mm  1.1 mm  0.025 70k 21 mm 5 mm 11 mm 5mm 0.80 mm 0.925 mm 1.2 mm  1.2 mm  0.025 70l 21 mm 5 mm 11 mm 5 mm 1.0mm  1.125 mm 1.4 mm  1.5 mm  0.025

[0097] TABLE 3B Apical Cleaning Instruments (25 mm) Total Length Abrad.Square Round Abrad Square Shank of File Portion Portion Portion TipPortion Portion Portion Inst. (L₁ +L₃ + Length Length Length Diam. Diam.Diam. Diam. No. L₄) (L₁) (L₄) (L₃) (D₁) (D₂) (D₃) (D₄) Taper 70a 25 mm 5mm 15 mm 5 mm 0.10 mm 0.20 mm  0.50 mm 0.50 mm 0.02  70b 25 mm 5 mm 15mm 5 mm 0.15 mm 0.25 mm  0.55 mm 0.60 mm 0.02  70c 25 mm 5 mm 15 mm 5 mm0.20 mm 0.30 mm  0.60 mm 0.60 mm 0.02  70d 25 mm 5 mm 15 mm 5 mm 0.25 mm0.375 mm 0.75 mm 0.80 mm 0.025 70e 25 mm 5 mm 15 mm 5 mm 0.30 mm 0.425mm 0.80 mm 0.80 mm 0.025 70f 25 mm 5 mm 15 mm 5 mm 0.35 mm 0.475 mm 0.85mm 0.90 mm 0.025 70g 25 mm 5 mm 15 mm 5 mm 0.40 mm 0.525 mm 0.90 mm 0.90mm 0.025 70h 25 mm 5 mm 15 mm 5 mm 0.50 mm 0.625 mm 1.0 mm  1.0 mm 0.025 70i 25 mm 5 mm 15 mm 5 mm 0.60 mm 0.725 mm 1.1 mm  1.0 mm  0.02570j 25 mm 5 mm 15 mm 5 mm 0.70 mm 0.825 mm 1.2 mm  1.1 mm  0.025 70k 25mm 5 mm 15 mm 5 mm 0.80 mm 0.925 mm 1.3 mm  1.2 mm  0.025 70l 25 mm 5 mm15 mm 5 mm 1.0 mm  1.125 mm 1.5 mm  1.5 mm  0.025

[0098] TABLE 3B Apical Cleaning Instruments (25 mm) Total Length Abrad.Square Round Abrad Square Shank of File Portion Portion Portion TipPortion Portion Portion Inst. (L₁ +L₃ + Length Length Length Diam. Diam.Diam. Diam. No. L₄) (L₁) (L₄) (L₃) (D₁) (D₂) (D₃) (D₄) Taper 70a 30 mm 5mm 20 mm 5 mm 0.10 mm  .20 mm  0.60 mm  0.60 mm 0.02  70b 30 mm 5 mm 20mm 5 mm 0.15 mm 0.25 mm  0.65 mm  0.70 mm 0.02  70c 30 mm 5 mm 20 mm 5mm 0.20 mm 0.30 mm  0.70 mm  0.70 mm 0.02  70d 30 mm 5 mm 20 mm 5 mm0.25 mm 0.375 mm 0.875 mm 0.90 mm 0.025 70e 30 mm 5 mm 20 mm 5 mm 0.30mm 0.425 mm 0.925 mm 1.0 mm  0.025 70f 30 mm 5 mm 20 mm 5 mm 0.35 mm0.475 mm 0.975 mm 1.0 mm  0.025 70g 30 mm 5 mm 20 mm 5 mm 0.40 mm 0.525mm 1.025 mm 1.1 mm  0.025 70h 30 mm 5 mm 20 mm 5 mm 0.50 mm 0.625 mm1.125 mm 1.2 mm  0.025 70i 30 mm 5 mm 20 mm 5 mm 0.60 mm 0.725 mm 1.225mm 1.3 mm  0.025 70j 30 mm 5 mm 20 mm 5 mm 0.70 mm 0.825 mm 1.325 mm 1.4mm  0.025 70k 30 mm 5 mm 20 mm 5 mm 0.80 mm 0.925 mm 1.425 mm 1.5 mm 0.025 70l 30 mm 5 mm 20 mm 5 mm 1.0 mm  1.125 mm 1.625 mm 1.7 mm  0.025

[0099] After the apical portion has been properly widened, thepractitioner selects a set of files having the appropriate length, suchas one of the sets presented in Tables 3A-3C. To ensure that the fileshave an appropriate working length, it may be necessary to place stopsaround the shank portions of the files identified for example at 76. Thepractitioner then selects an instrument from the set identified ashaving an appropriate length for introduction into the root canal downto the apical portion.

[0100] As indicated above, in this example, an instrument is selectedfrom the set detailed in Table 3B, which is shown in FIG. 1 as set 70.After selecting an instrument, the practitioner then determines, basedon feel and experience, whether the file is appropriately sized orwhether a larger or smaller file is needed. For instance, if thepractitioner selects instrument number 70 b from the set detailed inTable 3B and shown in FIG. 1 at 70 b which has a tip diameter of 0.15 mmand the file binds after insertion, then the practitioner would switchto instrument number 70 a which has a tip diameter of 0.10 mm.Similarly, if instrument number 70 b is too loose then the practitionerwould then switch to instrument number 70 c which has a tip diameter of0.20 mm. The practitioner then uses that appropriately sized instrumentto clean the apical portion of the root canal by hand. If thepractitioner concludes after using an appropriately sized file, thatfurther instrumentation is still needed within the apical portion thenthe instrument with the next largest file may be used It is typicallyunnecessary to use a third instrument with an even larger file afterusing a series of two instruments. However, the practitioner may cleanthe apical root portion with a series of more than two instruments asdeemed necessary by the practitioner in order to fully clean the apicalportion. This procedure is followed until an instrument has been usedthat has an abrading portion with a taper that is greater than 0.20 suchas instrument 70 d. Abrading portion 79 d of file 74 d has a taper thatis 0.025. If file 74 d is the first file inserted into the root canalthen it may be necessary to utilize one or more files with larger tipdiameters that also have abrading portions with a taper of 0.025.

[0101] While some of the files in the sets have abrading portions withtapers that are not identical. It is also within the scope of thepresent invention, to provide sets of instruments that have files withabrading portions that all have the same taper. For example, the taperof files 74 a-1 from tip 78 a-1 to the top end of the abrading portionmay be the same. The taper may also increase from file to file. In themethod of using such instruments, the common feature is that the lastfile used to clean the apical portion has a taper that is greater than0.02 to enable a gutta percha point having a conventional taper of 0.02to be easily inserted into the root canal as far as is needed toappropriately occlude the apical portion. Since it is generallynecessary to use only a few of the instruments in the set, it ispreferable that the majority of the abrading portions have tapers thatare greater than 0.02. Accordingly, only abrading portions 79 a-c havetapers that are 0.02 while the remainder of the abrading portions 79 d-1have tapers of 0.025.

[0102] Each file 74 of the file instruments designed for cleaning theapical root portion of a root canal is configured to have an abradingportion 79 along at least a portion of the length of file 74. The entirelength of each file 74 can be configured with an abrading portion 79,however, abrading portion 79 preferably extends from tip 78 part wayupward towards the top end of the file such that the remainder of file74 is relatively smooth. More particularly, each file is preferablyconfigured with an abrading portion along less than about half of thelength of the file and more preferably about one-third of the lengthbetween tip 78 and the top end of the file. The abrading portion 79 canhave a similar or identical configuration to the abrading portion of thefile or files used to clean the operative middle portion of the rootcanal or the files used to improve the access into the apical rootportion.

[0103] The length of a file such as apical portion files is sufficientsuch that when the files are inserted into the root canal the tips canat least approximately reach the apex and the abrading portion of thefiles can substantially contact and clean the pulp material in theapical portion of the root canal. Such file lengths are generally withina range from about 8 mm to about 35 mm, more typically in a range fromabout 14 mm to about 35 mm and most typically in a range from about 12mm to about 33 mm The length of the abrading portion is generally withina range from about 1 mm to about 35 mm, more preferably in a range fromabout 2 mm to about 16 mm and most preferably in a range from about 3 mmto about 6 mm.

[0104] The diameter of the abrading portion is generally within a rangefrom about 0.06 mm to about 1.4 mm As shown in FIG. 1, each successivefile has an abrading portion, identified as 79 a-1, which issuccessively larger in diameter at the top of the abrading portion thanthe abrading portion of the preceding file.

[0105] The diameter of the tips 78 a-c of each file are preferablyincreased incrementally such that each sequentially utilized cleaninginstrument has a slightly larger tip diameter than the precedinginstrument or the tip diameters may be about equal in diameter. Thediameter at the top end of the file is preferably greater than thediameter of the abrading portion ash shown in Tables 3A-3C. However, thediameter at the top end of the file can also be equal to or less thanthe diameter of the abrading portions or even the tip in someembodiments.

[0106] The abrading portion 79 of each file 74 of file instruments 70a-1 are preferably formed by twisting a blank so as to form a spiral.However, as discussed above, the blank may be shaped by any suitablemethod. The abrading portion 79 preferably has few spirals such that theaction of abrading portion 79 against the walls or surfaces of theapical portion of the root canal is relatively gentle. Such an abradingportion is less aggressive as fewer spirals results in tines that have awider angle.

[0107] Set 10 and set 40 are preferably disposed after use. However,since only one or two instruments from set 70 are used, it is preferableto replace or clean the instruments used from set 70. All of the sets ofinstruments described in this example may be sold together as acomprehensive kit or various sets may be grouped together as kitsintended for use with teeth of particular lengths. For example, the setsused in the tooth cleaned in this example which are detailed in Table1B, 2B and 3B may be sold together. Additionally, since set 10 and set40 are intended to be single use sets these sets may also be soldtogether as a single use disposable kit.

[0108] The present invention may be embodied in other specific formswithout departing from its spirit or essential characteristics. Thedescribed embodiments are to be considered in all respects only asillustrated and not restrictive. The scope of the invention is,therefore, indicated by the appended claims rather than by the foregoingdescription. All changes which come within the meaning and range ofequivalency of the claims are to be embraced within their scope.

What is claimed and desired to be secured by United States LettersPatent is:
 1. A method for cleaning the apical root portion of theoperative root canal of a tooth, the method comprising: obtaining atleast one apical portion cleaning instrument that has a file with anabrading portion for removing pulp material having a taper that isgreater than 0.20; and cleaning the apical root portion with the atleast one apical portion cleaning instrument by abrading the apical rootportion with the abrading portion of the file such that the apical rootportion is prepared to receive an endodontic point that has a taper thatis 0.20.
 2. A method as defined in claim 1, wherein the apical rootportion is cleaned after essentially all pulp material has been removedand cleaned from the operative coronal portion and the operative middleportion by flexing a file of an instrument to urge its abrading portionagainst root canal surfaces within the operative middle portion as theinstrument is rotated and moved in a cleaning motion in conformance withthe anatomical shape of the operative middle portion by following thecontours of the operative middle portion as a guide for movement of theinstrument, and without significantly extending the file of theinstrument into the apical root portion.
 3. A method as defined in claim1, further comprising: obtaining at least one apical portion cleaninginstrument that has a file with an abrading portion for removing pulpmaterial having a taper of 0.20; and cleaning the apical root portionwith the at least one apical portion cleaning instrument that has a 0.20taper before cleaning the apical root portion by abrading the apicalroot portion with the abrading portion of the file that is greater than0.20.
 4. A method as defined in claim 1, wherein the taper of theabrading portion of the apical root portion cleaning instrument is about0.25.
 5. A method for cleaning the apical root portion of the operativeroot canal of a tooth, the method comprising: obtaining a set of apicalportion cleaning instruments that each have a file with an abradingportion for removing pulp material, wherein at least one of the apicalportion cleaning instruments has an abrading portion with a taper thatis greater than 0.20; and cleaning the apical root portion with one ormore of the apical portion cleaning instruments such that the instrumentthat is last to be used in the apical root portion has an abradingportion that is greater than 0.20 to enable the apical root portion toeasily receive an endodontic point that has a taper that is 0.20.
 6. Amethod as defined in claim 5, wherein the apical root portion is cleanedafter essentially all pulp material has been removed and cleaned fromthe operative coronal portion and the operative middle portion byflexing a file of an instrument to urge its abrading portion againstroot canal surfaces within the operative middle portion as theinstrument is rotated and moved in a cleaning motion in conformance withthe anatomical shape of the operative middle portion by following thecontours of the operative middle portion as a guide for movement of theinstrument, and without significantly extending the file of theinstrument into the apical root portion.
 7. A method as defined in claim5, wherein the file of each instrument in the set of apical portioncleaning instruments terminates at a tip, wherein the tips havedifferent tip diameters and wherein the apical root portion is cleanedby sequentially utilizing apical portion cleaning instruments such thateach successive file has a greater tip diameter than that of thepreceding file.
 8. A method as defined in claim 5, wherein the taper ofthe abrading portion of the apical root portion cleaning instrument thatis used last to clean the apical portion has a taper that is about 0.25.9. A method for cleaning of the operative coronal portion, the operativemiddle portion and the apical root portion of an operative root canal ina tooth, the method comprising: obtaining at least one first endodonticinstrument having a file with an abrading portion for removing pulpmaterial, the file having a length corresponding to at least thecombined length of the operative coronal portion and the operativemiddle portion; removing and cleaning essentially all pulp material fromthe operative coronal portion and the operative middle portion byintroducing the file of the first endodontic instrument into theoperative middle portion and then flexing the file such that theabrading portion of the file is urged against root canal surfaces withinthe operative middle portion as the first endodontic instrument isrotated and moved in a cleaning motion in conformance with theanatomical shape of the operative middle portion by following thecontours of the operative middle portion as a guide for movement of thefirst endodontic instrument, and without significantly extending thefile of the first endodontic instrument into the apical root portion;obtaining at least one apical portion cleaning instrument that has afile with an abrading portion for removing pulp material having a taperthat is greater than 0.20; and cleaning the apical root portion with theat least one apical portion cleaning instrument by abrading the apicalroot portion with the abrading portion of the file such that the apicalroot portion is prepared to receive an endodontic point that has a taperthat is 0.20.
 10. A method as defined in claim 9, further comprising thestep of improving access into the apical root portion after the pulpmaterial has been essentially removed from the operative middle portion.11. A method for performing a root canal procedure, the methodcomprising: obtaining at least one apical portion cleaning instrumentthat has a file with an abrading portion for removing pulp materialhaving a taper that is greater than 0.20; and cleaning the apical rootportion with the at least one apical portion cleaning instrument byabrading the apical root portion with the abrading portion of the filesuch that the apical root portion; positioning an endodontic point thathas a taper that is 0.20 in the apical portion of the root canal oncethe root canal has been cleaned.
 12. A method as defined in claim 11,wherein the taper of the abrading portion of the apical root portioncleaning instrument is about 0.25.
 13. A method as defined in claim 11,further comprising the step of introducing a composition into the rootcanal around the endodontic point.
 14. A method as defined in claim 13,wherein the composition is polymerizable such that it polymerizes insitu.
 15. An endodontic instrument for cleaning the apical root portionof the operative root canal of a tooth, the instrument comprising a filehaving a length that is sufficient to extend to the apex of a rootcanal, wherein the file has an abrading portion extending from a tip ofthe file upward with sufficient length to enable at least the apicalportion of the root canal to be abraded, wherein the abrading portionhas a taper that is greater than 0.20 such that the apical root portionis prepared to receive an endodontic point that has a taper that is0.20.
 16. An endodontic instrument as defined in claim 15, wherein thetaper of the abrading portion of the apical root portion cleaninginstrument is at least about 0.225.
 17. An endodontic instrument asdefined in claim 15, wherein the taper of the abrading portion of theapical root portion cleaning instrument is about 0.25.
 18. A set ofinstruments comprising a plurality of apical portion cleaninginstruments adapted for cleaning the apical root portion of theoperative root canal of a tooth, each instrument in the set having afile with a length that is sufficient to extend to the apex of a rootcanal, wherein each file has an abrading portion extending from a tip ofthe file upward with sufficient length to enable at least the apicalportion of the root canal to be abraded, wherein the file of at leastone of the instruments has an abrading portion with a taper that isgreater than 0.20 so that the abrading portion with a taper greater than0.20 can be used in the apical root portion last to enable the apicalroot portion to easily receive an endodontic point that has a taper thatis 0.20.
 19. A set of endodontic instruments as defined in claim 18,wherein the taper of the abrading portion of the file of at least one ofthe instruments is at least about 0.225.
 20. A set of endodonticinstruments as defined in claim 18, wherein the taper of the abradingportion of the file of at least one of the instruments is about 0.25.21. A set of endodontic instruments as defined in claim 18, wherein thefile of each instrument in the set of apical portion cleaninginstruments terminates at a tip, wherein the tips have different tipdiameters and wherein the apical root portion is cleaned by sequentiallyutilizing apical portion cleaning instruments such that each successivefile has a greater tip diameter than that of the preceding file.
 22. Aset of endodontic instruments as defined in claim 18, wherein the fileof each instrument in the set of apical portion cleaning instruments hasessentially the same length.
 23. A set of endodontic instruments asdefined in claim 18, wherein some of the files of the apical portioncleaning instruments have abrading portions with tapers that are about0.20 and some of the files of the apical portion cleaning instrumentshave abrading portions with tapers that are about 0.25.
 24. A set ofendodontic instruments as defined in claim 18, wherein the file of eachinstrument in the set of apical portion cleaning instruments terminatesat a tip, wherein the tips have different tip diameters and wherein theapical root portion is cleaned by sequentially utilizing apical portioncleaning instruments such that each successive file has a greater tipdiameter than that of the preceding file; and wherein the apical portioncleaning instruments that have relatively small tip diameters haveabrading portions with tapers that are about 0.20 and wherein the apicalportion cleaning instruments that have relatively large tip diametershave abrading portions with tapers that are greater than about 0.20.